The present invention relates to a polymer alloy of polyarylene thioether (hereinafter referred to as "PATE"), which is excellent in various properties, for instance, impact strength and is uniformly blended, a process for producing the polymer alloy and a composition containing the same.
Recently, PATE has been used in various fields as a crystalline, thermoplastic resin which is excellent in heat-resistance, moldability, chemical-resistance, oil-resistance, hot water-resistance, flame-resistance, mechanical properties, such as, rigidity. However, since PATE is insufficient in toughness, impact strength and film properties such as sliding property, plating property, adhesiveness and further is apt to cause flash at the time of injection molding, improvement of these properties have been strongly requested.
Hitherto, as a method to improve an impact strength, a method of melt-blending an impact modifier with PATE has been proposed.
For instance, Japanese Patent Application Laid-Open (KOKAI) No. 56-118,456 (1981) discloses an impact-resistant resin composition comprising:
(i) 100 parts by weight of poly(arylene sulfide) or a modified polymer thereof, and
(ii) not less than 1 part by weight and less than 100 parts by weight of a block copolymer which contains not less than one polymer block mainly consisting of a vinyl aromatic compound and not less than one polymer block mainly consisting of a conjugated diene compound, and the vinyl aromatic compound in said copolymer contains more than 75 wt % of block homopolymer segment and/or the diene compound in said copolymer contains more than 15 wt % of 1,2-vinyl bonding.
U.S. Pat. No. 4,395,512 discloses a poly(phenylene sulfide) resin composition comprising (a) 100 parts by weight of a poly(phenylene sulfide) resin, (b) 10 to 300 parts by weight of an inorganic filler and (c) 1 to 100 parts by weight of a fluorocarbon rubber which shows the Moony viscosity (ASTM D1646) of 5ML1+10(100.degree. C.) to 300ML1+10(120.degree. C.). Further, U.S. Pat. No. 4,581,411 discloses a composition for molding, which contains poly(arylene sulfide) and a polymeric rubber selected from the group consisting of silicone rubber, ethylene-acryl rubber, ethylene propylene rubber, ethylene propylene-diene rubber and poly(butyl acrylate) rubber in an amount that the polymeric rubber can improve an impact strength and/or a crack-resistance of the product.
However, since the melt-processing temperature of PATE is very high, the conventional impact modifier such as natural rubber, SBR, NBR, isoprene rubber of the modified products thereof, is easy to decompose thermally during melt-processing, and accordingly such a modifier is not suitable as a material to improve impact strength.
Further, the modifier of olefin rubbers such as ethylene-propylene rubber (EPR), is small in thermal decomposition and its cost is relatively low. However, since the compatibility of the modifier of olefin rubbers with PATE is extremely poor, its effect of improving the impact-strength is low. Moreover, there is a problem that the appearance of a molded product obtained from the composition is prone to be very poor.
Still further, although the conventional modifier of polyacrylic ester rubbers does not necessarily thermally decompose easily during melt-blending, the material is still insufficient as an impact modifier for PATE.
Further, Japanese Patent Publication No. 53-13,469 (1978) discloses a method for improving the moldability of PATE by blending polystyrene, a thermoplastic resin, with PATE. However, a compatibility of polystylene with PATE is poor and even when they are blended in an usual manner, it is difficult to obtain a desirable fine dispersion of polystylene in PATE. Namely, such method is not necessarily sufficient.
Generally in polymer blending, it is a well known fact that good dispersibility of added polymer and strong interfacial adhesion between dispersed polymer and matrix polymer are important factors manifesting the physical characteristics of blended products. However, among conventional blending methods so far proposed, there is not known any method with sufficient dispersibility and interfacial adhesion.
As a method to improve various features, such as impact strength, of PATE effectively and economically, the present inventors have extensively studied to mix radically polymerizable monomers with PATE in a different manner and method from those of mixing conventional modifier and to polymerize the monomer, objecting good dispersibility and excellent interfacial adhesion of thus polymerized monomer with PATE.
As a result of such extensive study, they have found that a polymer alloy of PATE prepared by polymerizing at least a part of radically polymerizable monomer, for instance, an acrylic ester monomer, within internal pores of PATE particles, can have an excellent impact strength by manifesting good dispersibility and interfacial adhesion of the radically polymerized monomer with PATE. In addition to the finding, they have also found that by adding fibrous fillers, such as glass fibers in particular, impact strength of the polymer alloy can be improved remarkably because the radically polymerized monomers present in the interface of the fillers and PATE. Based on these findings, the present inventors have attained the present invention.